P3 potentials have been widely used to study normal human cognitive functions and assess cognitive impairment in patients. However, several studies suggest that the usefulness of P3 potentials as practical assessment tools is limited, because their neural mechanisms remain unclear thus far. The aim of the present study was to investigate the neural mechanism of P3 potentials by using the socalled P3-like potentials in rats.

Chapter 1 presents a review of the relevant literature on the neural mechanisms of P3 potentials and P3-like potentials in animals.

Chapter 3 describes the investigations of the regions that generate P3 potentials, such as the ACC and hippocampus, conducted using the rat model. Experiment 7 showed that the latency of P3-like potentials from the ACC was shorter than that of potentials from the hippocampal CA1 region. Moreover, only highly deviant stimuli elicited P3-like amplitudes in the ACC, while the target stimulus elicited P3-like amplitudes in the hippocampal CA1 region, irrespective of stimulus deviation (Experiment 8).

In Chapter 4, on the basis of the results presented in chapters 2 and 3, a model describing the process of P3 generation is presented. Further, future studies are proposed.

journal title

Bulletin of the Graduate School of Integrated Arts and Sciences, Hiroshima University. I, Studies in human sciences